Wireless access systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless access system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.) among them. For example, multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, and a Single Carrier Frequency Division Multiple Access (SC-FDMA) system.
Currently, it is expected that the trend of mobile wireless networks will be toward the denser deployment of small cells for capacity enhancement. By increasing the number of small cells, end-users can be physically located closer to the network and therefore, the data capacity would be significantly improved.
However, when considering the deployment of large number of small cells, some technical issues made from the differences between small cell and macro cell deployment should be carefully identified and solved. As an example, although the turn on or off of cells is an important characteristic for macro cell deployment in terms of energy saving, such an aspect should also be emphasized for small cell deployment. The reason is that the dynamic turn on or off of large number of small cells might have some RAN impacts.